This invention relates to an improvement in a process for extracting tungsten from alkali metal tungstate solutions, the improvement being removing bromine from major portion of the stripped organic prior to reuse of the organic in the extraction step.
U.S. Pat. Nos. 4,175,109, and 4,360,503 and 4,374,099 describe processes for recovery of tungsten from alkali tungstate solutions by solvent extraction with an organic extractant solution consisting essentially of tertiary amines in a solvent which is essentially aromatic.
The problem that exists is that the organic extractant solution becomes contaminated during continued use by various bromine-containing compounds, such as 2-bromonaphthalene, 1-bromo-2,4-diethyl-6-methylbenzene, and others. This contamination causes the phase separation in the tungsten solvent extraction process to be much slower and reduces the rate of throughput to the point at which insufficient tungsten values are provided for subsequent processing.
The spent organic phase can be replaced entirely by new material. However, this is expensive and causes a problem of disposal of the spent materials.
Therefore, a process for removing the bromine compounds from the organic so that the organic can be reconstituted and reused would be an advancement in the art.
Other prior art processes relating to recovery of tungsten include U.S. Pat. Nos. 3,158,438 to Kurtak; 3,256,058 to Burwell; 3,293,004 to Musgrove et al; and 4,360,502 to MacInnis et al; South African Pat. No. 684,892 and British Pat. No. 1,240,524.